Application of distributed energy system in agricultural circular economy

With the current social environment and energy issues becoming more and more prominent, in order to promote the rational use of resources, some rural areas have carried out exploration and research on the agricultural circular economy model. Based on "four-in-one" mode of traditional agricultural circular economy, combined with distributed energy system, absorption refrigeration and denitration process, we proposed "five-in-one" agricultural circular economy model. "Five-in-one" refers to the model of "farming- biogas- energy supply- greenhouse- agricultural planting". The "five-in-one" system mainly adds gas generator sets and cold storage to convert the produced biogas into income. The "five in one" has changed the pattern that agriculture can only export low-end agricultural products, forming a new model for the union of workers and peasants. It constitutes an integrated energy and ecological utilization system, promotes the development of renewable energy, and increases the supply of clean and high-quality energy in rural areas and converts them into income. The combination of livestock and poultry breeding, production of biogas, distributed energy, greenhouses and agricultural planting, the five are interdependent and integrated, forming a comprehensive utilization system of agriculture, energy and ecology. Taking a biogas tank with a gas production capacity of 1 000 m3 as an example, 365 000 m3 of biogas can be produced for gas-fired units to generate electricity continuously. Each cubic meter of biogas can generate 2.6 kW•h, and the total power generation capacity is about 936 MW•h. The cold storage provides energy by using low-quality heat energy. According to the gas-fired unit's power generation efficiency of 34%, the biogas power generation waste heat resource is used for direct-fired absorption type chiller refrigeration, and the daily cooling capacity is 5 887 kW•h. The 1 000 m3 biogas tank can produce 1550 t of organic fertilizer and 9 000 tons of biogas slurry, which can reduce 760 tons of carbon dioxide. In the "five in one" model, the main problem is that the construction cost and key technical fields are immature. It is necessary for the state to provide subsidies in accordance with new energy installed power generation, and to provide subsidies for distributed energy system construction, subsidies for biogas production construction, and operational subsidies. State Grid Corporation should acquire the on-grid electricity in the agricultural circular economy model in accordance with the solar power grid-connected electricity price. The National Energy Administration should give the operating companies carbon trading rights in accordance with 50%~60% of the carbon emission reductions of biogas power generation, in order to facilitate the initiative in the future carbon trading market and promote the development of circular economy in rural areas. If the technology is not mature, experts should be organized to discuss, build a pilot project, and study the technical problems and improvement programs in the operation process. We will adjust the agricultural structure and industrial construction, gradually improve the scientific research and production technology system, and promote successful experiences to the whole country. © 2018, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.